import { v4 as uuidv4 } from 'uuid'; 
export const getUUID =()=>{
   let uuid_token=localStorage.getItem("UUID")
    if(!uuid_token){
     uuid_token=uuidv4()
     localStorage.setItem('UUID',uuid_token)
    }
    return uuid_token
    // 最后return很重要！！！！
}
